Scissors jack

ABSTRACT

A scissors jack of the &#39;&#39;&#39;&#39;double&#39;&#39;&#39;&#39; linked type utilizing six pairs of linkages supported upon a base plate and wherein both the lowermost and uppermost linkage sets are interconnected by correlation means in the form of gear teeth to produce a synchronized relationship between the linkages during extension and retraction of the jack, and particularly insure complete jack linkage retraction.

[ 1 Aug. 15, 1972 United States Patent Andersen-Vie FOREIGN PATENTS OR APPLICATIONS SCISSORS JACK Inventor: Axel Andersen-Vie, Jackson, 657,637 1/1929 France......................254/l22 Mich.

[731 Assignee: Ryersen S. Haynes,

Jackson,

I Primary Examiner0thell M. Simpson Att0meyBeaman & Beaman Mich.

ABSTRACT [22] Filed: Aug. 3, 1970 A scissors jack of the double linked type utilizing six pairs of linkages supported upon a base plate and wherein both the lowermost and uppermost linkage sets are interconnected by correlation means in the Appl. No: 60,565

228 0 M5 5M WW2 m m 4 H. 5 m .c U l m m S k U.. .F H N 555 form of gear teeth to produce a synchronized relationship between the linkages during extension and retrac- [56] References Cited UNITED STATES PATENTS tion of the jack, and particularly insure complete jack linkage retraction.

1,135,440 4/1915 Cremieu-Javal...........254/l22 2 Claims, 2 Drawing Figures SCISSORS JACK BACKGROUND OF THE INVENTION The field of the invention pertains to scissors jacks using pivotally interconnected linkages in conjunction with a screw operator for extending and retracting the linkages for lifting purposes.

Scissors jacks have previously utilized correlation means between corresponding sets of linkages attached to the base plate. Such correlation means usually take the form of gear segments concentrically related about the pivot axes of the linkages on the base plate as typified by U.S. Pat. Nos. 1,701,314; 1,736,202 and 2,796,150 and are usually employed to assure proper sequence of linkage operation, and minimize the possibility of binding as the jack is raised or lowered.

However, scissors jacks have the disadvantage of a relatively limited degree of extension unless long linkage dimensions are employed, and while scissors jacks have been used in the servicing of automobiles, such as in the changing of a tire, present automotive suspension systems, combined with low ground clearance, require a jack with a low retracted height which can extend sufficiently to lift an independently sprung wheel. The present invention overcomes difficulties in the use of scissors jacks with modern automobiles, and constitutes an improvement over conventional scissors jack construction.

SUMMARY OF THE INVENTION It is an object of the invention to provide a scissors jack capable of sufiicient extension to raise an automobile a sufficient height to permit a tire change, even though the wheels may be independently supported, and yet is capable of sufficient retraction of the linkages to permit the jack to be easily stored and readily inserted under a vehicle having limited road clearance.

A further object of the invention is to provide a scissors jack of the double linkage type wherein-six sets of linkages are employed in the jack to define two linkage systems and correlation means are utilized to insure proper sequence of operation of the linkages and, particularly, permit the jack to retract to a concise dimension.

The jack of the invention includes a base plate upon which a pair of linkage sets are pivotally mounted. Each linkage set consists of substantially identical links held together in spaced relationship by spacers or similar structure. Third and fourth sets of linkages are pivotally mounted upon the first and second sets of linkages supported on a base plate, and fifth and sixth sets of linkages are, in turn, pivotally mounted upon the upper ends of the third and fourth linkage sets. A cradle member is connected to the upper ends of the fifth and sixth sets, and includes means defined thereon for cooperation with the load to be engaged and lifted.

Gear segments are mounted upon the lower end of the first and second linkage sets for cooperation with each other, and gear teeth are also located at the upper ends of the fifth and sixth sets of linkages for cooperation with each other, and concentrically defined with respect to the pivot axes of the associated links. Thus, as the jack is extended and retracted, both the lowermost and uppermost sets of linkages will produce equal degrees of pivoting and movement as the jack is operated, and the structure insures that the jack operates smoothly, and retracts to the most concise configuration possible.

In order to aid in the concise retraction of the jack, the central or intermediate linkages, constituting the third and fourth sets of linkages, are received within the lowermost or first and second linkage sets, and the uppermost linkage sets, i.e., the fifth and sixth linkage sets, are received within the third and fourth linkage sets. In this manner the linkage sets will substantially nest when the jack is retracted.

A further object of the invention is to provide a double linkage scissors jack particularily usable with automobiles, and of economical manufacture, dependable and safe operation, and of a concise configuration.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects and advantages of a scissors jack constructed in accord with the invention will be appreciated from the following description and accompanying drawings wherein:

FIG. 1 is an elevational view of a scissors jack constructed in accord with the invention, the full lines illustrating the jack in its retracted condition, and the dotted lines indicating the position of the jack components in the fully extended position, and

FIG. 2 is a side, elevational view similar to FIG. 1 wherein the full lines indicate the retracted condition, and the dotted lines indicate the extended relationship of the linkage sets.

DESCRIPTION OF THE PREFERRED EMBODIMENT From the drawings, the relationships and details of the assembled jack, and the components thereof, will be apparent. A base plate 10, which is formed of sheet metal by a stamping operation, defines a lower surface 12 adapted to rest upon the ground or supporting surface upon which the jack is mounted. The U-shape of the base results in identical upstanding base portions 14 in which a pair of spaced, parallel pivot pins 16 and 18 are mounted.

The lowermost or primary set of linkages are mounted upon the pivots l6 and 18 of the base plate. The links 20, of which there are two of identical configuration, constitute the first set of linkages, and the links 22, which also constitute an identical pair, constitute the second set of linkages. The linkage sets 20 and 22 are each provided with an outer or free end in which pivot holes 24 and 26 are defined, respectively, for receiving the screw block or nut, as will be later described.

Correlation means are interposed between the linkage sets 20 and 22, and consist of gear teeth 28, definedupon linkages 20, and gear teeth 30 defined upon linkages 22. The gear teeth 28 and 30 are identical and concentrically related to the pivot pins 16 and 18, respectively, and intermesh during all phases of jack operation and orientation. In this manner equal angular movements of the linkage sets 20 and 22 about their associated pivot pins is assured. v

A nut 32 is pivotally mounted upon journals 34 received in the holes 24 of the linkages 20, and a block 36 is pivotally mounted in the holes 26 of the linkages 22 upon journals 38. A screw 40 extends through a bore 42 defined in the block 36 and is threaded into a threaded bore 44 defined in the nut 32. The screw 40 includes an operating head 46 to which a wrench or handle may be attached for rotation of the screw, and the screw includes a thrust bearing 48 which bears against the block 36. Thus, in the well known manner, rotation of the screw 40 adjusts the distance between the nut 32 and the block 36 to provide extension and retraction of the jack.

The third and fourth sets of linkages are pivotally mounted on the journals 34 and 38, respectively. The third set of linkages includes an identical pair of links 50 which are inset adjacent their lower end at 52, FIG. 2, and the fourth set of linkages consists of links 54 which are mounted on the outside of the links 50. The lower end of the link sets 50 and 54 pivotally associate with the journals of the nut 32 and block 36, in a known manner, and the link sets are centrally pivotally interconnected by a pivot pin 56. A spacer sleeve 58, FIG. 2 is interposed between the links 50 and 54 to maintain the spacing of the sets.

The uppermost ends of the link sets 50 and 54 are provided with pivot pins 60 and 62, respectively, which constitute the support means for the fifth and sixth linkage sets 66 and 64.

The fifth link set 66 consists of a pair of links pivotally connected at its lower end to the pivot 60, and the link set 64 is pivotally connected to the link set 54 by the pivot pin 62. Spacers on the pivot pins maintain the spacing between the links of a set.

The upper ends of the link sets 64 and 66 are pivotally connected by pivot pins 68 and 70 to a cradle member 72. The cradle member 72 constitutes the load engaging element of the jack and includes a load receiving recess 74 defined therein which cooperates with an edge or other downwardly extending portion of the load to be lifted.

The upper ends of the links of the link sets 64 and 66 are provided with identical gear teeth 76 and 78, respectively, which intermesh at all conditions of the jack, and the teeth are concentrically related to its associated pivot pin. Thus, as the jack is extended and retracted, the correlation means between the link sets 64 and 66, as produced by the gear teeth 76 and 78, assures like angular pivoting and movement of the links relative to the pivots 68 and 70 and 60 and 62 as the jack is extended and retracted and thus binding is minimized and the load will be properly raised as the jack is extended;

During retraction of the jack the presence of the gear teeth 28 and 30, and the gear teeth 76 and 78 insures that the linkages 50 and 54 will be nested within the configuration of the link sets and 22, and the links 64 and 66 will nest between links 50 and 54 to the fullest possible extent, thereby insuring that the folded or retracted position of the jack, as illustrated in full lines in the drawing, is at a minimum, and thus the jack may be readily stored, handled and inserted below a low clearance vehicle having a deflated tire.

It is to be understood that various modifications to the jack of the invention may be apparent to those skilled in the art without departing from the spirit and scope thereof.

L l c iuble linked scissors jack characterized by its ability to correlate linkage movement and concisely retract comprising, in combination, a base plate, a first set of links pivotally mounted on said base plate for pivotal movement about a first axis a second set of links pivotally mounted on said base plate for pivotal movement about a second axis parallel to and spaced from said first axis, meshing gear teeth defined on said first and second sets of links, respectively, concentric to said first and second axes for producing simultaneous and correlated pivotal movement of said sets of links, meshing links of said first and second sets of links being coplanar, third and fourth sets of links pivotally connected to said first and second set of links, respectively, at locations spaced from said first and second axes, respectively, said links of said third and fourth sets having ends, a pivot pin pivotally interconnecting said third and fourth sets of links intermediate their ends, the transverse spacing between said first and second sets of links being greater than that of said third and fourth sets of links whereby said third and fourth sets of links are disposed between said first and second sets of links, fifth and sixth sets of links pivotally connected to said third and fourth sets of links, respectively, the transverse'spacing between said third and fourth sets of links being greater than that of said fifth and sixth sets of links whereby said fifth and sixth sets of links are disposed between said third and fourth sets of links, a cradle member having a load receiving surface defined thereon, said fifth set of links having upper ends pivotally connected to said cradle member for pivotal movement about a third axis, said sixth set of links having upper ends pivotally connected to said cradle member for pivotal movement about a fourth axis substantially parallel to and spaced from said third axis, said cradle member being disposed intermediate the transverse spacing of the links of said fifth and sixth sets of links, meshing gear teeth defined on said fifth and sixth sets of links, respectively, concentric to said third and fourth axes for producing simultaneous and correlated pivotal movement of said fifth and sixth sets of links relative to each other and said cradle member, and screw means interconnecting said first and second sets of links for extending and retracting said sets of links, upon full retraction of said links said third and fourth sets nest intermediate said first and second sets and said fifth and sixth sets nest intermediate said third and fourth sets to minimize the retracted height of the jack.

2. In a double linked scissors jack as in claim 1 wherein said gear teeth defined on said first and second sets of links are of equal pitch diameter and tooth configuration, and said gear teeth defined on said fifth and sixth set of links are of equal pitch diameter and tooth configuration. 

1. A double linked scissors jack characterized by its ability to correlate linkage movement and concisely retract comprising, in combination, a base plate, a first set of links pivotally mounted on said base plate for pivotal movement about a first axis a second set of links pivotally mounted on said base plate for pivotal movement about a second axis parallel to and spaced from said first axis, meshing gear teeth defined on said first and second sets of links, respectively, concentric to said first and second axes for producing simultaneous and correlated pivotal movement of said sets of links, meshing links of said first and second sets of links being coplanar, third and fourth sets of links pivotally connected to said first and second set of links, respectively, at locations spaced from said first and second axes, respectively, said links of said third and fourth sets having ends, a pivot pin pivotally interconnecting said third and fourth sets of links intermediate their ends, the transverse spacing between said first and second sets of links being greater than that of said third and fourth sets of links whereby said third and fourth sets of links are disposed between said first and second sets of links, fifth and sixth sets of links pivotally connected to said third and fourth sets of links, respectively, the transverse spacing between said third and fourth sets of links being greater than that of said fifth and sixth sets of links whereby said fifth and sixth sets of links are disposed between said third and fourth sets of links, a cradle member having a load receiviNg surface defined thereon, said fifth set of links having upper ends pivotally connected to said cradle member for pivotal movement about a third axis, said sixth set of links having upper ends pivotally connected to said cradle member for pivotal movement about a fourth axis substantially parallel to and spaced from said third axis, said cradle member being disposed intermediate the transverse spacing of the links of said fifth and sixth sets of links, meshing gear teeth defined on said fifth and sixth sets of links, respectively, concentric to said third and fourth axes for producing simultaneous and correlated pivotal movement of said fifth and sixth sets of links relative to each other and said cradle member, and screw means interconnecting said first and second sets of links for extending and retracting said sets of links, upon full retraction of said links said third and fourth sets nest intermediate said first and second sets and said fifth and sixth sets nest intermediate said third and fourth sets to minimize the retracted height of the jack.
 2. In a double linked scissors jack as in claim 1 wherein said gear teeth defined on said first and second sets of links are of equal pitch diameter and tooth configuration, and said gear teeth defined on said fifth and sixth set of links are of equal pitch diameter and tooth configuration. 